Single-phase earth fault diagnosis method and device

Abstract

The invention discloses a fault diagnosis method which is used for determining whether a single-phase earth fault occurs in a low current earth system and determining the position of a fault point. The method comprises the following steps of: (102) synchronously acquiring the power frequency voltage of a busbar of the low current earth system and the current traveling wave of all outgoing lines in real time; (104) determining an outgoing line with turbulence in all the outgoing lines when the turbulence occurs in the low current earth system; (106) determining whether the single-phase earth fault occurred in the low current earth system according to the power frequency voltage; and (108) determining the outgoing line with the turbulence as a faulty outgoing line to obtain the distance between the acquisition point and the fault point on the current traveling wave of the faulty outgoing line when the single-phase earth fault occurred in the low current earth system. The invention discloses a fault diagnosis device. The single-phase earth fault of the low current earth system can be detected according to the fault diagnosis method and device.

Description

technical field [0001] The invention relates to a power system fault detection technology in the field of power system relay protection, in particular to a single-phase ground fault diagnosis method and device. Background technique [0002] The small current grounding system refers to the system with a small fault current when a single-phase grounding fault occurs, specifically refers to the neutral point not grounded, the neutral point through the arc suppression coil or the neutral point through the high resistance grounding system, commonly known as the small current system. When a single-phase ground fault occurs in a small current system, since it does not constitute a short-circuit circuit, it is not necessary to quickly cut off the faulty line and stop the user's power supply. According to statistics, single-phase ground faults account for more than 70% of all faults in the entire power distribution system. In order to ensure the reliability of power supply, my count...

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Problems solved by technology

However, the modulus traveling wave cannot be obtained directly in the power system, and the three-phase traveling wave obtained by the three-phase mutual inductor needs to be transformed into a modulus traveling wave through phase-mode transformation. In most small current grounding systems, single-phase grounding is not Tripping is required, so usually only two mutual inductors and zero sequence transformers are installed, so three modulus traveling waves cannot be obtained, and thus single-phase ground fault diagnosis cannot be achieved

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